A Brave New World
by DawnRulz
Summary: Doctor Strange feels guilty about Tony's death and tirelessly tries to find a way to save him. Fortunately for him, the Death Stone possessed by the Master of Death is one way. He finds the location of the MoD in another dimension and seeks her help. The Avengers and Harry journey on towards a brave new world where the sun finally starts to shine. Fem!Harry, AU for both.
1. Chapter 1

**A Brave New World**

_**Where it all starts... Again!**_

**AN: Here's my first crossover and my first work in both the fandoms! Hope you like this… Sorry in advance for any grammatical error.**

**Standard disclaimers apply to all chapters. I own neither the Marvel Comics, MCU or the Harry Potter Universe.**

**Happy reading!**

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**Prologue**

Harriet "Harry" Potter looked around solemnly at the destruction surrounding her, black flames burned nearly everything as far as her eyes could see. She was in an unplottable location near the Amazon forest. She had her phoenix feather wand in one hand and a small pouch hung from the waist belt of her dragon hide uniform.

"Expecto Patronum!" A regal projection of a phoenix emerged from her wand. "Mission accomplished." Harry relayed to her Phoenix. "To the big boss, Nix." The phoenix materialized leaving a trail of blue as it disappeared.

Harry transformed into her animagus form- a majestic jet black phoenix with intelligent emerald eyes. She flew up and watched on till the flames died down to reveal a huge crater in the place of what used to be a mysterious tomb. One which Harry had just examined, excavated to scour the place for anything of interest and value.

Harry, who would be turning twenty six in a day, worked as an independent curse-breaker for the Ministry. She had joined the auror corps after the 'Battle of Hogwarts' nearly a decade ago, but quickly lost interest in fighting battles she wanted no part in. She still wanted to help others and her 'hero complex', as Hermione always called it, was still strong; however, she was _exhausted_. No matter how hard she tried, there was no changing the world, much less saving it.

The crimes never ended. Even with Voldemort gone, the peace was short lived. Another rogue, uncaptured death eater had taken his place. He too was defeated in a few months, but the damage was done- muggles and muggleborns along with a few aurors became casualties. There were thieves, serial killers, abusers, rapists and so many other evil-doers; Harry couldn't save everyone.

There was no changing the world. The world didn't want to be saved. Peace was short-lived, even that always came at a heavy price.

_Balance. _For every positive thing in the world, exists something bad. Harry had learned that lesson the hard way- many times over.

Harry was just about to teleport when a voice rang behind her. "Wait!"

A strange orange portal opened and a tall aristocratic man, wearing a long red cloak seeped in magic stepped through.

"Are you the Master of Death?" The strange man inquired looking straight at Harry.

Harry ignored him but she was scared. She had no backup and this man had addressed her by the title no one except Hermione, Ron and Dumbledore (possibly) even knew of. She flew a bit further but he followed her by flying towards her. The man was powerful, Harry noticed, as he was capable of unsupported flight in human form.

"Please hear me out." The man said pleadingly. "I am the Sorcerer Supreme of a different dimension. If you're the Master of Death, I require a favor from you. It is of utmost importance."

Harry examined the man closely. He looked weary and worn. He looked to be healing from a big fight if the gashes on his cheeks bones, highlighting how prominent and angled his jaws were really, looked fresh. He looked earnest and desperate.

Something resounded within Harry and she decided to listen to his story. She transformed back to her human form after landing on the ground with the Sorcerer following.

"What do you require from the Master of Death?" Harry inquired with a quirked eyebrow.

"Uh, I suppose Mistress of Death would be more appropriate." He looked surprised.

"I'm Harry." Harry supplied amused.

"Strange." The man said casually and Harry frowned preparing tell him off for insulting her but he must have sensed it. "My name is Doctor Strange."

Harry slightly blushed realizing her mistake and smiled apologetically. "And what brings you here, Dr. Strange? Are you a doctor or a sorcerer?"

"Both actually." Strange replied. "I am in search of the Master, or rather, the Mistress of Death, as the world I come from has lost its best defender."

Doctor Strange explained how the Mad Titan, Thanos, had destroyed worlds and had wiped out half the universe. Harry listened with rapt attention, not willing to interrupt the most unbelievable story involving aliens, technological advancements fit for Sci-fi and time travel of all things.

"_If _I were to believe your story, what do you require from me?" Harry asked trying to process everything the sorcerer had retold.

* * *

The man, Tony Stark, sounded like a kindred spirit. He seemed to have taken the same road harry had once taken upon Dumbledore's instruction, sacrificing herself in order to save the world, as had this Tony Stark. Only there was no horcrux in his head to be destroyed, so he had stayed dead. He had a daughter as well. The little girl, unlike her, would grow up in a loving environment with superheroes surrounding her but she would never really understand why her father had to leave for a very long time.

"You are in possession of the Death Stone." Strange answered hesitantly. "I believe it can negate the powers of using the Infinity Stones."

Harry pursed her lips in disbelief. She had dropped the Resurrection Stone in the Forbidden Forest and had never thought much about it. To her, the Master of Death was just one of the many titles and monikers she had. It didn't mean anything. The most powerful was in Dumbledore's tomb, it would always be Dumbledore's wand to her. The Cloak was her family heirloom that she hoped to pass on to her children or godchildren she would no doubt be surrounded by.

"Listen, Doctor Strange, I'm afraid I have no idea how to use the resurrection stone. It is my responsibility to warn you of its many dangers. The one who used it originally became addicted to meeting the shade of the person he had lost. It drives you crazy. And I also believe it's quite cruel to the souls to be summoned as shades with no purpose other than to tempt them into seeing what they have left behind. The resurrection stone brings in nothing but trouble." Harry informed him seriously.

She had understood it at Seventeen, the only reason she had let go of the Stone was because she thought she was going to die and join her parents and Sirius. That it was of no use to her dead.

"I was led to believe that the one you call the resurrection stone was part of the death stone. Not the Death stone itself. You need three artefacts, possessed by the Master of Death, to bring a deceased one back to life, as long as it hasn't passed on to the other side, the Void, whatever you want to call it." Strange explained cautiously. "This dimension was the only one I could find where someone had become the Master of Death."

"All three hallows, you say?" Harry asked suspiciously. "And it can bring back anyone?"

"Not anyone, Ms. Harry." Strange said softly. "I only researched how to counter the effects of the Infinity Stones. There's no way to bring someone back from the dead- that I know of."

"Of course." Harry agreed sadly. "I still don't know how to help you. I know where the Hallows are- I want to be there when you use them. I really don't want them falling into the wrong hands, no offence to you."

"Only you can use the Death Stone." Strange informed. "There is a ritual you need to perform, I will summon the spirit energy, and the artefacts should merge into the Death Stone."

Harry thought his words over once again. This was a pretty bad idea. She might lose her beloved cloak. The only heirloom of her family, it was one of its kind. There was a chance, though Harry had gotten pretty good at reading someone's intention, that everything could go horribly wrong.

On the other hand, she wanted to help the sorcerer who was trying so hard to amend the mistake he had committed. Save a worthy life; give a little girl her father back, save the husband of a good selfless woman, give a bunch of people their friend back, save the mentor of a teenager who needed a father figure, and most importantly, bring back the defender of an entire dimension.

"Alright, I will help you." Harry said decisively. Strange gave a small relieved smile.

* * *

Harry apparated him just outside the Forbidden Forest. Strange barely even flinched.

"I dropped it somewhere inside this forest." Harry confessed worriedly. The only indication that Strange gave he was surprised was a slight raise of his brows.

"Most magical things emit energy which should be quite to track." Strange assured her. He weaved his hands in complex patterns and various symbols appeared gleaming in dark green. Harry wondered if Hermione would be able decipher them as Harry's knowledge of ancient runes was limited.

"Interesting." Strange muttered. "There seems to be multiple magical signatures all over the place. Human, animal and inanimate objects containing high energies."

Strange's magic grew darker when he gestured towards Hogwarts; it appeared blue when he pointed towards the Forest and when he scanned her, his symbols showed different colors. Strange's brows knit together showing his confusion.

"Um, I thing I know what the problem is." Harry smiled sheepishly. "There's too much magic around us. Can you track, like, specific energies?"

"There's a Sanctum here?" Strange asked interested. "Our Sanctum is in the middle of London. And yes, I can track the other artefacts if they have the same energy."

"Here's the Cloak." Harry handed her Cloak of Invisibility carefully. Strange examined it for a second before weaving his hands in complex motions making different symbols, Harry still didn't know, appear. "What's a sanctum?"

"It is a place of teaching, healing and a line of defence against magical and dimensional threats." Strange explained distractedly, his concentration fully on the Cloak.

"How interesting." Harry commented. "Then you were probably asking about Hogwarts. It's a school that teaches magic. It's the school I went to when I was eleven."

"Eleven?" Strange asked in surprise. Harry briefly explained about witches, wizards and Hogwarts. Strange listened intently without even slowing down whatever magic he was doing. Harry rambled about Hogwarts and the magical world for a few minutes anxiously. The distraction mainly for her sake as she had little idea what was happening. The second he did anything to harm her Cloak, she was attacking him with her most powerful spell.

Finally, there was beam of light from the halo of what looked like a compass of some sort. Harry was impressed as it pointed towards the direction of Dumbledore's grave.

"It looks like one of them is that way." Strange commented slightly out of breath. "From the look on your face I suspect you already knew that."

Harry shrugged unrepentantly and showed him the Elder wand she had apparrated to bring.

"I only told you that I had lost the Stone, nothing about the want." Harry reminded him. "Can you find where it is?"

"Of course." Strange said slightly offended. "The problem is that there appears to be a multitude of magical species on the way with no way of finding out which ones are hostile." Strange looked at Harry with narrowed eyes. "Unless, of course, you already know how to get past them."

"Assume all of them are hostile." Harry piped in. "So we have two ways to do this. Either I go with my Cloak and hopefully get the Stone without letting anything know I'm in there; or I fly there and land in a safe spot to grab the Stone."

"You mean we have one option. You fly and get the Stone back." Strange said annoyed. "I will know when the beam extends that you have decided to make a run for it."

Harry hummed noncommittally and transformed into her Phoenix form. She followed the golden beam emitting from the compass and finally reached the middle of the forest clearing where she vividly remembered the shades of her parents and godfather she had desperately summoned. She picked up the Stone with her beak not trusting her human self with the Stone still. Willing herself not to think of her deceased loved ones, she flew towards Strange as quickly as possible.

Harry transformed back and laid the three hallows together.

"It would be better to do the ritual where it is unlikely we will be disturbed." Strange said without preamble. Harry agreed quietly.

"Would my house be ok?" Harry asked. "It has the best wards and protection." With a hesitant nod from Strange, Harry put the Hallows in a small pouch that had another undetectable extension charm and apparated them outside Grimmauld Place. She took a piece of paper with the address and told him how to get past the Fidelius charm.

* * *

As the old grandfather clock of her Godfather's house chimed twelve times, signifying the start of Harry's Twenty Sixth year, they started the ritual. Strange had briefed her about the ritual over a glass of pumpkin juice and leftover treacle tart.

Strange began the ritual and Harry carefully did her part. It took only a few minutes before the Hallows merged into one brilliant oval black stone. One might mistake it for a random pebble if not for the purple energy almost electricity surrounding it.

Harry held it in her hands uncertainly. Strange gave her an encouraging nod.

"I wish to summon Tony Stark from the dead, please." Harry ordered like she was at a restaurant. She grinned cheekily as Strange rolled his eyes exasperatedly. Harry was about to try again but the place grew colder and there was darkness everywhere.

A lone figure emerged from a cloud of smoke. It almost looked like a male human if not for his glowing gold eyes unnaturally gleaming from his dark face, black matted hair, his eight foot body encased in black and gold armor, a helmet with gold horns and he held a sword emitting the same purple energy as the new Stone.

"You summoned me, my Mistress?" He asked in the deepest voice Harry had ever heard. "I am Heimdall, also the newest God of Death."

Harry looked at Strange who appeared just as shocked as her. What had she gotten mixed up in now? _I hate my birthday, _Harry complained in her head loudly.

* * *

**AN: Do let me know what you guys think!**


	2. Chapter 2

**A Brave New World**

**AN: THANK YOU SO MUCH for the response to my first chapter. Hope this finds you all well and distracts you from whatever problems you are facing right now.**

**We are all in this together!**

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**_Chapter 1_**

Harry stared at Heimdall awkwardly. She had never imagined Death to have a physical manifestation. Sure, she had heard the tale of the Peverell brothers who supposedly met Death and were granted three most powerful objects but that's all it ever was. A story. Not even Dumbledore or Hermione had put much thought into it. They too were under the impression that it was the three brothers who had crafted the Hallows to serve their own agenda.

Now though, looking up at Heimdall or Death's ethereal gold eyes, she wondered what the title 'Master of Death' truly entailed.

"Mistress," Heimdall interrupted Harry's thoughts, "What can I do for you?"

"Um, well, you see…" Harry struggled to find her voice. "Harry. Just call me Harry."

"Very well, Lady Harry." Heimdall sounded pleased.

"I am the Sorcerer Supreme. Strange." Strange cut in. "I am the one who requested Miss Harry's help on an important task."

"Go on, Protector of Time." Heimdall said formally. Harry assumed that that title belonged to the wielder of the Time Stone.

"It is a really long story. But the short version is that a man, from a different dimension, used the Infinity Stones to stop an intergalactic supervillain named Thanos who had wiped out half the living beings of the universe." Strange gave the cliff-notes version.

"I know of Thanos, the Mad Titan." Heimdall said sharply. "You wish to bring back one of your fallen heroes? The Avengers?"

"I wasn't aware the other dimensions knew about them, but essentially, yes." Strange informed. "Tony Stark to be specific."

"If Lady Harry so wishes, it is possible to summon the one you have lost." Heimdall answered thoughtfully.

Harry nodded in agreement. "So, uh, I can call you Heimdall right?" Heimdall gave a nod. "If you truly believe this is real, and I can save an innocent life then I agree."

"Lady Harry, if you doubt the credibility of the Sorcerer's words, perhaps you might want to examine what has really happened." Heimdall suggested after a lengthy pause.

Strange looked slightly irritated and Harry wanted to assure him that it was just a bit unbelievable-

"I mean I am not the legilimens, and I don't have any Veritaserum or a pensieve on hand." Harry explained more to herself.

"If there is a way to prove my story I will gladly do it." Strange said calmly. "However, you have my word as the Sorcerer Supreme and a Doctor that everything I have told you is the truth."

"I was simply advising Lady Harry that we could travel to your home dimension and see for ourselves how great a loss you have truly suffered." Heimdall deadpanned. "Lady Harry should not have even a miniscule amount of doubt about summoning your hero back."

"That it acceptable." Strange replied. Harry was relieved she would be making an informed choice instead of some hearsay.

Heimdall took out his sword and stabbed the ground making strange runes hover over the carpet on the floor, before Harry could memorise it, they apparated away.

* * *

In an instant, Harry was hovering over what looked like a lake house in the middle of nowhere. She let out a surprised scream just as Heimdall and Strange floated on either side of her. There was a gathering of some sort, a funeral Harry guessed due to all the black formal wear the people were wearing.

A red haired woman turned on a projection of some sort and a man in his fifties appeared as a hologram. A little girl who was clutching the red head's hand exclaimed happily, "Daddy!"

Everyone in the clearing looked like they had swallowed a bitter pill and carefully kept their eyes on the projection.

"No. Stark can come back!" Strange shouted. "Stop it."

"Only your soul is here, Sorcerer. They cannot hear you." Heimdall remarked coolly. Harry hid her surprise. The man in the hologram, Tony Stark, kept talking. Harry was listening attentively.

**_"-Everything is going to work out exactly the way it's supposed to. I love you 3000."*_**

Harry understood why Strange was trying as hard as he was to bring Tony Stark back after hearing that message. He had sacrificed himself believing that was the only way.

"Heimdall, I really do want to bring this man back." Harry declared. It seemed like Heimdall had been watching a blond man- who was one of the biggest men she'd ever seen, excluding Hagrid. Probably the biggest muggle she had ever seen.

"If that is what you wish, Lady Harry." Heimdall said and they were back in Grimmauld Place in seconds.

* * *

Harry woke up with a jolt, she was pleased to see Strange was also slightly disoriented.

"That was certainly an experience." Harry commented.

"Harry, you're alright!" Hermione Granger exclaimed, catching Hermione in a fierce hug. "What happened? I came over to find you and your date unconscious. I was just analysing your drinks for potions and stuff."

Harry stopped Hermione before she started asking too much. When Harry took a good look at her friend, Hermione appeared completely frazzled. She still had on her Ministry robes, she had come over directly from work, Harry guessed.

"Hermione, breathe." Harry tried helping her. "I didn't know you were coming over. I thought we weren't supposed meet until tomorrow." Harry thought over what could have happened. "Is it Teddy? Is he alright?"

"I believe she thinks we were on a date for some reason and I drugged you." Strange remarked offhandedly.

Harry looked at Hermione in disbelief and embarrassment. Hermione looked down guiltily not meeting Harry's eyes. Harry jumped as the Floo lit up in green flames. Ron Weasley appeared with his wand at the ready carrying a barely awake Teddy Lupin.

"Aunty Harry!" Teddy greeted sleepily. "I thought we were gonna see you at Grandma Molly's place for the super secret party."

"Hey, Teddy bear." Harry glared at Ron and Hermione. "Ron, take Teddy to his room and put him to bed." Harry looked at Hermione and curtly said, "Explain," and sunk into the comfy armchair gesturing at everyone to sit down.

"Um, well, you see, Harry." Hermione mumbled uncharacteristically. "Brian. Do you remember the Daily Prophet and the Ministry liaison? So he came into my office at around midnight carrying an article written by Rita Skeeter about you. Usually I tell them to bin whatever that woman writes, but she had pictures this time. It looked like you two were standing outside while the Fidelius was in effect. That cow has insinuated many untoward things about you two. Since I knew you were on that assignment and wasn't seeing anyone or you would tell me, I came here to let you know." Hermione hadn't gone on such a tangent since their Hogwarts days. "I came over and saw you with this - er gentleman, both technically not breathing and on the floor, I freaked out and called Ron. I didn't know what else to do!"

Harry felt exhausted and wished she could hide behind the wall, like Ron was currently to avoid his fiancé's tirade. She took a look at Strange who was visibly impressed.

"The gentleman, as you put it, is Doctor Strange. You remember the Master of Death?" Harry briefly explained everything that had transpired.

"So you want to bring a dead guy back to life in another earth and this strange bloke is not from here?" Ron finally made his presence known, arms crossed. "Well at least you weren't dating the guy or anything. No offence mate, but you're kind of ol- ow," Hermione reached out to pinch his arm.

"So I'm fine. I'll just bring Tony Stark back to life and carry on like it never happened." Harry said decisively. "Just stay here and watch over Teddy while we go do this thing."

* * *

Heimdall chose that moment to materialise. He gave off waves of guilt despite his poker face. Harry just knew that something was off looking at his demeanour.

"Everything alright, Heimdall?" Harry asked grimly.

"Mistress. Lady Harry. It appears as though doing this will have far reaching consequences." Heimdall said cautiously. He looked uncertain. "I cannot disclose everything at the moment. However, my best suggestion is for you to leave your realm and try to join the Midgardians we visited."

"What do you mean you won't disclose everything to Harry?" Ron demanded angrily. "Aren't you supposed to be the Master of Death? You know the _master_?"

"Lady Harry might be the Mistress of Death, however, I am bound by the Laws of the Universe." Heimdall responded coolly. Harry was glad she didn't have to diffuse another heated argument.

"Heimdall, what are these consequences?" Harry asked. "Anything you can say about it is fine."

Heimdall looked at Harry for a second, his golden eyes piercing into her emerald ones before slowly revealing of another world changing event.

"Lady Harry your life is in grave danger." Heimdall said candidly. "You have already unearthed a rather unexpected hidden danger. You have a large army of a tribe of some sort after your life. You have inadvertently destroyed and looted the realm of a sacred race of magical creatures."

"Is there any way to prevent it from happening? If we compensate perhaps, or maybe the Ministry of Magic could create an alliance of good faith." Hermione was throwing out possible courses of action.

"Relax Hermione." Ron interjected. "We don't know for sure we can trust this bloke. What if he's just saying that to whisk Harry into trouble himself?"

Harry and Hermione knew for certain that Heimdall could be telling the truth. Harry's recent mission to the Amazon was infact to examine the suspected home of the blood goblins. Harry had destroyed what she thought was a tomb but could have been anything really. She even had everything she had scoured on her person.

"What happens if I die?" Harry asked casually much to the displeasure of everyone in the room.

"I see possibilities, not the future." Heimdall glanced at Strange as he said that. "The worst probable future is you are killed by blood thirsty dwarf-like creatures. The magical community goes to war against all the scorned dark creatures and meets its end. This extends to the non-magical community and the human race of this planet will be eradicated."

There was silence as they mulled over the news. "What's our best case scenario?" Harry asked quietly.

If Heimdall was surprised, he didn't show. "Lady Harry, you will leave this reality and save the world. Your Minister and Lady Hermione will return what you have stolen and appease the creatures with a vow to not disturb the tribe in the future. That is the safest outcome."

"What about Harry? Will she be happy over in a different world? What if her life here then? She has a godson, a job, her friends and family-" Hermione was close to tears. "Perhaps the Department of Mysteries and our department can come up with a satisfactory plan."

"Hermione, maybe it's a good thing y'know?" Harry tried. "I mean maybe going away for a while could be a very good thing. I'll definitely miss you guys but I'm tired of doing this over and over again."

"Hey, don't go jumping to conclusions now." Ron interrupted. "We haven't even decided if these guys are telling you the truth."

"Not to mention the whole inter-dimensional immigration." Doctor Strange who was simply observing pointed out. "However, with so many new changes and half the dimension's living creatures having been suddenly brought back, you will have the best chance at making a new life with us. As a fellow wielder of the Mystic Arts, I would offer sanctuary at any of our Sanctums."

The Sorcerer Supreme had been glimpsing the future from the moment Death had materialised. He had a vague idea why the former Guardian and Gatekeeper of Asgard was insistent on having Harry Potter around a certain other Asgardian.

"Then it's settled." Harry declared loudly. "If the offer extends to my godson as well, I'd be delighted to take you up on that."

"I don't see why that would be a problem." Strange replied.

"I guess I'll ask Teddy and go to update my will and handle my finances." Harry said slightly overwhelmed. "I'd have to quit my job of course and turn in the findings from yesterday…"

Harry was moving around from room to room getting everything ready. She retrieved a few shrunk muggle suitcases and muggle bank cards. She hurriedly pulled out a bunch of parchments from a trunk, wrote a few things and signed each one off with a blood quil.

"You almost seem prepared to leave a moment's notice, Harry." Hermione accused looking at Harry's uncharacteristic organization skills. "Think about Teddy and how he would feel about all this."

"It's something I've been thinking of for quite some time 'Mione," Harry replied running to the owlery. She tied her parchments, gave the destination for each envelope before waking Teddy up.

Harry explained the situation best as she could to the young metamorphmagus who was disoriented but understood that he would be with Harry. They had discussed the possibility of them moving to another country.

Ron seemed to be in an altercation with Stranger and Heimdall. Harry gave a familiar mirror to Hermione and hugged Ron and Hermione tightly. "Take care all of you. Tell Molly I won't make it to the party after all."

* * *

Harry blinked back her tears and looked at the two mystical beings who had changed Harry's life in less than a few minutes. "Let's do this thing."

Heimdall nodded and struck his sword into the ground. Amid ancient times, Teddy's excited squeal and rainbow visions, they arrived at the lake from earlier.

Surprisingly, one Tony Stark had also joined the little group of travellers.

"What the f- peanuts!" Tony exclaimed, summing up everything perfectly and promptly collapsed.

* * *

**AN: Yup that escalated quickly. Here's the next chapter, finally.**

**How are you all doing!? Hopefully we will all make it through safely. I started my job a few weeks after posting this story and it has been a crazy ride so far.**

**I'm sorry if it's rushed and I'm too tired to look for mistakes but I really needed to write something non work related this week or I'm gonna go insane. So I downloaded the app on my phone.**

**Let me know what you all think. Long story short, I'm still not over Endgame**

**PS take care and stay safe everyone. Lots of love.**


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